Submitted to: Proceedings Great Plains Soil Fertility Conference
Publication Type: Proceedings
Publication Acceptance Date: January 6, 2010
Publication Date: March 2, 2010
Citation: Liebig, M.A., Halvorson, A.D. 2010. Change in Soil Phosphorus as Influenced by Crop Sequence, Tillage, and N Fertilization. p. 205-210. IN: A.J. Schlegel and H.D. Bond (Eds.) Great Plains Soil Fertility Conf. Proc. Vol. 13. Denver, CO. March 2-3, 2010. Kansas State Univ. Interpretive Summary: Crop sequence, tillage, and N fertilization can influence soil properties, including the availability of nutrients necessary for plant growth. Within the portfolio of essential plant nutrients, phosphorus is particularly important for crop production in the northern Great Plains as soils in the region are inherently low in plant-available P. Recent increases in P fertilizer costs have placed a premium on identifying management practices that efficiently use plant-available soil P. To help address this need, a study was conducted to determine the effects of crop sequence, tillage, and N fertilization on plant-available soil P within a long-term cropping systems experiment near Mandan, ND. Results from the study found soil P to be greater under crop-fallow as compared to continuous cropping, and lower under treatments receiving moderate-to-high levels of N fertilizer relative to treatments receiving no or low levels of N fertilizer. Increased grain removal with continuous cropping and moderate-to-high levels of N fertilizer likely enhanced depletion of soil P. Outcomes from this study underscore the importance of tailoring soil fertility recommendations for dryland cropping systems based on the frequency of fallow and use of N fertilizer.
Technical Abstract: Data from a long-term cropping systems experiment near Mandan, ND were used to evaluate management effects on residual plant-available soil P. Management variables assessed were crop sequence [spring wheat-fallow (SW-F) and spring wheat-winter wheat-sunflower (SW-WW-SF)], tillage (conventional-, minimum-, no-tillage), and N fertilization (0, 22, and 45 kg N/ha for SW-F and 34, 67, and 101 kg N/ha for SW-WW-SF). Available soil P was affected by crop sequence (SW-F was greater than SW-WW-SF; P=0.0358) and N fertilization (0/45 kg N/ha was greater than 22/67 and 45/101 kg N/ha; P=0.0016) 12 years after an initial, one-time application of fertilizer P. Between 1991 and 1996, depletion of soil P was prevalent across treatments, and was enhanced by N fertilization or intensive tillage in SW-F. Within SW-WW-SF, depletion of soil P was most pronounced under minimum- and no-tillage at N rates greater than or equal to 67 kg N/ha. Results from this study should prove useful in subsequent efforts to quantify treatment effects on P-use efficiency.